1. Field of the Invention
The present invention relates to a method of manufacturing ceramics. More particularly, the invention relates to a method of removing under heating a film of an elastic material (hereinafter referred to as "elastic film") applied for compression to a shaped body.
2. Description of the Prior Art
Since silicon ceramics such as silicon nitride, silicon carbide, sialon and the like, alumina ceramics, zirconia ceramics and so on are stabler at a high temperature and less susceptible to oxidation corrosion or creep deformation than metals, studies have been actively made for utilizing them as engine parts.
When ceramics for use as engine parts are shaped by mold shaping, injection molding, cast molding and so on, density variation is produced at various portions of the shaped body, so that the characteristics of the resulting sintered bodies are not satisfactory. For this reason, there has been employed a technique that after the whole ceramic shaped body obtained by the above shaping methods is hermetically covered with rubber, compression is isotropically applied to result in the density distribution of the shaped body being uniform.
Although the operation of removing the coated rubber film from the shaped body is ordinarily manually performed, there often occurs in the case of engine parts with a complicated configuration, such as a turbine rotor, that blade can be broken by mistakes during removing the covering rubber film, resulting in the article being defective. Further, since such operation is time consuming, and can not be done by a person other than a skilled person, it is unsuitable for mass production.
In order to resolve such problems, previous attempts involve removal of the covering rubber film through firing in an electric furnace, but it often happens that the rubber penetrates into pores of the ceramic body, which causes the production of cracks.